Land Use Issues
by Leslie Schaffel
Leaky Soil
Lesson 1
Introduction:
Many types of materials cover the surface of the Earth. Each of these materialshas characteristics and qualities that can be both advantageous and disadvantageousto the animals and plants that inhbait the surroundings. This project examinesthe ability of the water to pass through various types of soil- an importantconsideration for farmers and home gardeners.
Organization and Materials:
This project is best suited for groups of two or three students. Activitytakes about 50 minutes.
Per Group: Various soil samples to be studied (peat moss, potting soil,sand, pebble, clay soil, and so on)- one half metric cup of each, papercups, plastic cups, pencils, two popsicle sticks per cup, one paper towel,water, a clock or watch with a second hand.
Procedure:
1. Have students examine each sample and list its characteristics.
2. Direct pupils to use a pencil to poke ten or twelve holes in bottom ofeach paper cup.
3. Have students place a piece of paper towel in the bottom of each papercup to prevent the granules of each sample from falling out.
4. Ask students to fill each of the cups exactly half-full with the varioussamples and label each container with the name of its contents.
5. Instruct students to place two popsicle sticks across the top of theplastic cups to form a bridge and set the paper cups on top of the sticks(thtis allows the water to flow into the plastic cups).
6. Tell students to fill each paper cup (one by one) with water and timehow long it takes before water begins to seep through into the plastic cups.Have them record the results.
7. Discuss the findings.
Conclusion:
Results will depend on the samples used. Some samples (peat moss, pottingsoil) allow water to pass through very quickly compared to others, suchas sand. However, those same samples retain more water than sand does.
Dirt Cheap
Lesson 2
Introduction:
Depending on the geographical location, the surrounding environment, limaticconditions, and other factors, soil can be composed of many different materials.Soil composition in turn affects the plant life- and subsequently the animallife- that inhabits the particular area.
Organization and Materials:
Individuals or pairs of students can complete this activity. This activitywill take one 50 minute period.
Per Group: Newspaper to cover desk, a plastic bag of soil, a piece of whiteconstruction paper (twelve inchesnby seventeen inches), one large toothpick,a magnifying glass, and a sheet of paper to record data. (Upon completionof the activity, have students fold the white paper and funnel the soilback into the bags.)
Procedure:
1. Begin the activity with a brief description of what covers the Earth.
2. Today we are going to look at one of the materials that cover our Earth-soil. Does anyone know what soil is?
3. Distribute the soil samples, white construction paper, toothpicks, andmagnifying glasses.
4. Instruct the students to empty the bag of soil onto the white paper.Students should be encouraged to keep the soil on the white paper throughoutthe activity. After the bags have been emptied, have the students observetheir sample, instructing them to (a) separate into groups the various kinddsof substances they find (using the toothpick), and (b) make a list of thevarious substances discovered.
5. Discuss the findings with the class.
Conclusion:
Soil is composed of bits of wood, leaves, roots, insects, plants, and smallstones. As the organic substances die and decay, they turn into soil.
Soil Shake
Lesson 3
Introduction:
As we dig in our gardens or yards we often notice that the composition ofthe soil changes the deeper we dig. The many different kinds of materialstht make up soil form layers, depending on their composition or relativeweights. In this project various soil samples are mixed with water to demostratehow sediment layers are formed.
Organization and Materials:
Divide the class into groups of three to four each. This activity will takeone 50 minute period.
Per Group: Soil samples (approximately one half metric cup each of humus,garden soil, peat moss, clay, and so on), a jar and lid for each sample,water, magnifying glass.
Procedures:
1. Have students place approximately six centimeters of each soil samplein clean jars and label each jar.
2. Instruct the students to examine the soil sample in Jar 1 and list itscharacteristics.
3. Have students fill the rest of the jar with water and put the lid on.
4. Shake the jar for thirty seconds and observe and describe the results.Has the water changed? Describe the soil at the bottom.
5. Have the students observe the soil and water in the jar for one or twominutes and list their observations.
6. have students repeat steps 2 through 5 for each sample.
7. Have students compare findings for the various samples.
Conclusion:
Soil is composed of numerous particles, ranging from minute sandlike piecesto somewhat larger pieces of ravel or wood. when soil is mixed with waterand allowed to settle, layers are formed. The bottom layer contains thelargest and heaviest particles, with successively higher layers containingsmaller and smaller particles. The lightest particles float on the surfaceof the water.
Soil Conservation
Lesson 4
Introduction:
Discuss erosion and strip planting, the process of planting different cropsin strips or sections. This is useful when armers are planting row cropslike corn on sloping land. The corn must be carefully weeded and the groundtends to erode. By planting bushy, cover crops in alternating strips withthe corn, the erosion is lessened.
Organization and Materials:
This activity is best suited for groups of 3 or 4. This activity could take2-50 minute periods to construct, and a week or two to show the growth ofthe grass.
Per group: Three large flat pans, potting soil, grass seed water, and smallrocks or driveway gravel.
Procedures:
1. Label the first pan Terracing. Pour a 1/2-inch layer of potting soilin the center of the pan, about on inch cmaller than the outside of thepan. Pack it down and place a wall of gravel or small rocks around it tokeep it in place. Place a second 1/2-inch layer on top of the first, makingit one inch smaller than the bottom layer. Place a wall of rocks aroundit. Make a top layer one inch smaller than the middle layer and fence itwith a wall of rocks. Spread grass seeds evenly over each layer.
2. Label the second pan Contour. Make a large mound of soil inthe centerof the pan. Firm the soil by patting it carefully and forming ridges aroundit. Make ther idges 1/2 inch apart. Plant grass seeds inthe ridges.
3. In the third pan, make a mound of soil and pack it as in the secon pan.In this pan, make ridges up and down the mound like ther idges on an umbrella.Plant grass seeds in the ridges.
4. Water each pan to moisten the soil and place the three pans in a warm,sunny spot.
5. When the grass seedling are one inch taall, water heavily.
Conclusion:
Discuss where erosion is seen. Terracing and contour plowing both help toprevent erosion.
Tree Harvesting:
Lesson 5
Introduction:
Two methods lumbermen use for harvesting trees are selective cutting andtotal deforestation. Try this experiment to see which is better for thesoil.
Organization and Materials:
This activity is suited for groups of 3-4 students. One 50minute periodis needed to set up and the experiment and another class period a week later(after the seedlings have grown an inch) is necessary.
Per grop: 2-9 x 13 baking pans, potting soil, grass seeds and water.
Procedures:
1. Fill each pan with potting soil to a depth of one inch.
2. Sprinkle grass seeds evenly over the potting soil in each pan.
3. Water the pans and place them in a warm, sunny spot. Water the pans daily.When the seedlings re one inch high, you are ready to finish the experiment.
4. Pull all of the grass seedling out of the center of one pan making athree inch strip of bare soil from one end of the pan to the other. Thisis total deforestation.
5. Tilt the pan so the strip of bare soil runs downhill. Water the soil.What happens to the bare spot?
6. Pull only the tallest grass seedlings from the other pan. Pull seedlingsfrom all parts of the pan, but be careful not to leave any bare spots. Thisis selective cutting. Water this pan. What happens?
7. What could be done to prevent erosion of land that has already been deforested?
Conclusion:
The students should find that the soil should erode and wash to the bottomof the pan. The seedling should hold the soil in place. Totally deforestedareas can be replanted with seedlings. (Explain that many times lumber mendo this when they cut all of the trees in one area.)